Apparatus for stringing rackets



Nov. 30, 1937. L. c. DOLL 2,100,948

APPARATUS FOR STRINGING RACKETS Filed NOV. 25, 1936 4 Sheets-Sheet 1 Nov. 30, 1937. L. c. DOLL APPARATUS FOR STRINGING RACKETS 4 Sheets-Sheet 2 Filed Nov. 25, 1936 n a r Nov. 30, 1937. L. c. DOLL APPARATUS FOR STRINGING RACKETS 4 Sheets-Sheet 5 Filed Nov. 25, 1936 will, u m A mm R Ev mm hm I h x Yw Ma Q O O J D D Q W Q \h 4wh uh Patented Nov. 30, 1937 UNITED STATES PATENT OFFICE,

APPARATUS FOR STRINGING RACKETS Laurance C. Doll, Ithaca, N. Y., assignor to Doll Air-Stringer of America, Inc., Ithaca, N. Y., a corporation of New York Application November 25, 1936, Serial No. 112,807

17 Claims.

' in any manner.

A still further object of the invention is to provide apparatus of the foregoing character embodying a stand with a head thereon and upon which turrets are mounted for the support of a tennis racket and a String tensioning device, the turrets being adjustable to present a string passed through the desired openings in a racket frame in line with the pulling force exerted by the tensioning device.

Another object of the invention is to provide a support for the tennis racket while being strung, the support including sets of pins that have removable rubbercaps thereon engageable with the inner face of the racket frame.

With the above and other objects in view that will become apparent as the nature of the invention is better understood, the same consist in the novel form, combination and arrangement in parts hereinafter more fully described, shown in the accompanying drawings and claimed.

In the drawings:--

Figure 1 is a side elevational view of a' tennis racket stringing apparatus constructed in accordance with the present invention and illustrating the tennis racket support and string tensioning device mounted upon a head at the upper end of a standard;

Figure 2 is a top plan view with a tennis racket illustrated by dotted lines in its supported position;

Figure 3 is a vertical longitudinal sectional view taken on line 3-3 of Figure 2, showing the air operated devices for locking the tennis racket support or turrets and the tensioning device against rotary movement;

Figure 4 is a cross-sectional view taken on line 44 of Figure 2 showing an adjusting screw for a pair of supports for a tennis racket;

Figure 5 is a horizontal detail sectional view taken on line 55 of Figure 3 showing the tensioned string gripping jaws in their released position; 7

Figure 6 is a horizontal sectional view, similar to Figure 5, showing the string gripping jaws in gripping engagement with a string;

Figure 7 is a detail sectional view taken on line 1-1 of Figure 3, showing the string gripping jaws and the support thereforcarried by a fluid operated piston; r t

Figure 8 is a detail sectionalview taken on line 8-8 of Figure 1, showing the t-readle for operating the pressure fluid control valve;

Figures 9 and 10 are detail sectional views taken respectively-on lines 9--9 and l0l0 of Figure; Figure 11 is a detail sectional view taken on line H-II of Figure 3;

Figure 12 is a fragmentary elevational. view, partly in section, showing one of the rubber capped pinsfor engagement with a tennis racket;

Figure 13 is a detail sectional view taken on line Y l3-l3 of Figure 1, showing control valve; and V r v Figure 14 is a bottom plan view of the ratchet base plate of the tennis racket supporting turret.

Figure '15 is a sectional view of the valve shown in Figure 13. V g

The tennis racket stringing apparatus com prises a frame structure including a footed floor plate from which rises a sectional telescoping the pressure fluid tubular standard comprising sections 2i and 22 a maintained in adjusted positions by the set screw 23, the upper end of the standard section 22 receiving a socket portion 24 depending from a head plate 25, that is rigidly secured to the upper end of the standard section 22. A turret support I 26 for a tennis racket is rotatably mounted upon i one end of the head plate 25, the latter being preferably of a configuration in plan view as illustrated in Figure2, saidturret support comprising a circular ratchet base plate 21 that has a stud support 28 anchored centrally thereto by means of screws 29 that pass upwardly through openings 3!! in the ratchet base plate 21 for threaded engagement with the stud support 2 8 as shown in Figure 3. Pairs of horizontal arms i32 and 3334 extend at right angles to each other from the upper end of the stud support 28 and are braced byradial webs 35 as shown in Figures 1 and 3. The turret support 26 is rotatably adjustable upon one end of the head plate 25, the same beingiretained in position thereon by means of a stud bolt 36 passing upwardly through the head plate 25 for threaded engagement with an opening in the stud support 28 as shown in Figures 3 and 4. A circular series of ratchet sockets or depressions 3'? is formed in the lower face of the ratchet base plate 21 and with which a tensioned ratchet pin 38 is associated, a fluid pressure operated pin to be presently described also being associated with the ratchet base plate 2'! for holding the same against rotary movement and for anchoring the turret support in position.

Supporting and holding devices for a tennis racket are carried by the arms 8! .to 34at the upper end of the stud support 28, the upper sides of the arms 3! to 33 having key slots 39 therein for the mounting of the tennis racket holding devices while a cooperating holding device is rigidly connected to the arm 34. As shown in Figures 2 and 3, a block 48 is adjustably mounted in the arm 33 and is anchored in position by the set screw 4| and the block 42 is permanently attached as at 43 to the outer end of the opposite arm 34. As shown in Figures 2 and 4, a block 44is slidably mounted in each key slot 39 of the arms 9| and 32 and are adjustable towards and away from each other by means of a turn buckle screw 5having a swivel support 46 intermediate the ends thereof above the stud support 38, the opposite threaded ends of the screw buckle freely. extending through the blocks441and threading through nuts 4'! mounted in sockets 48 in the: blocks 44 and restrained from movement therein, one end of the screw 45 projecting outwardly of a block 44 and carrying an operatinghead 49. Upon rotation of the turn buckle screw 45, the blocks 44 are moved towards or away from each other.

As shown in Figures 3, 4, and 12, the spindle 58 is vertically adjustable in a socket 5!, formed in each of the blocks 49 and 44and isretained in adjusted positions by a set screw 52, the upper end of the spindle 59 carrying a block 53 upon which a tennisracket frame 54 is adapted to be supported, pins 55 rise from the upper end of each spindle 58 above the block 53 and having a rubber thimble 55 thereon for engagement with the inner sides of the tennis racket frame 54as shown in Figures 3 and 4 in a manner to prevent injury thereto.

A horizontal screw 42a is carried by the upper end of the rigid block 42 and has a block 530, at the inner end thereof for the support, of the tennis racket frame and from which pins 55a rise for cooperation with the other sets of pins 55;

A string stretching and tensioning device 5? is carried by the other end of the head plate 25 that includes a ratchet base plate 58 rotatably supported on the head plate 25 by means of the tubular screw 59, the lower face of the plate 58 having a circular series of sockets therein similar to the sockets 8'! in the plate 2'! and with which a tensioned ratchet pin 38a is associated, a block 59 rises from the plate 58 and is secured thereto as ,at 68 and said block 59 has a passage 5| therein that communicates with one end of a cylinder 52 projecting horizontally and laterally of the upper end of theblock 59. A piston 53 is reciprocably mounted in the cylinder 62 and is normally retained at the end of the cylinder adjacent the upper end of the block 59 by means of a coil spring 5 3 having the outer end thereof surrounding a pin 55 carried bythe outer closure plug 65 for the cylinder 62, while the inner end of the spring extends into a socket 8'! in the piston 63. The upper side of thecylinder 52 is longitudinally slotted as at 68.

A string gripping device is carried by the piston 53 and extends downwardly through the cylinder slot 58 for attachment to the piston and as shown in Figures 3 and 5 to 7, a block 69 carries a stem 10 that depends therefrom through the slot -68 with the block and stem anchored to the piston 83 by the screw pin H. The upper side of the block 99 is cut away to providei a reess extending longitudinally thereof with plates '52 secured to the upper sides of the block at the outer edges to overlie the recess with the adjacent edges of the plates 12 spaced from each other. A pair of channel-shaped string gripping jaws 13. is slidably mounted in the recess in the block 69, the closed sides of the channel jaws facing each otherand having secured thereto a string gripping strip 14 having the working face thereof serrated'similar to a file to prevent slippage of a string, but being of a character which will not injure or mar the string. The mounting for each jaw 73 includes a pair of links 15 for each jaw, the links being pivoted as, at 16 at their outer ends to the block 69 while the in-,

ner ends thereof are pivoted as at H to the jaws 13.. A coil spring 75a is associated with each jaw 73, one'end thereof being anchored as at-18 to the jaw, while the other end is anchoredeas at "E9 to the pivot 16 for the link 15. The jaws 13 are manually shifted by means of the pins .88 as shown in Figure 3, with the tension of the springs 19 to assume the separated position shown in Figure 5 for the placement of a tennis racket string 8! therebetween and when'pressure onthe jaws 13 is relieved, the springs-15a cause the jaws to assume the position shown in Figure 6 with the file strips 14 in gripping engagement with the stringspBi.

Pneumatic devices are associated with the ratchet base plates 21 and 58 for holding them against rotation on the head plate 25 and also for operating the piston 63, the degree-of pres sure of the pneumatic devicesbeing registered on the dial or gauge 82 setinto the head plate 25 as shown in Figures land 2. An air conduit 83 from a source of compressed air or other fluid communicates with the multi-way valve 84 in the hollow footed base 28, the valve being operated by the rod 85 .thatcarries treadles 86 and 86m shown in detail in Figure 8. A conduit 81 from the multi-way valve84 extends upwardly through the tubular sections 2| and 22 of the standard and passes outwardly of the upper end of the standard section 22 as shown in Figure 1 for communication with an angle-fitting 88 that communicates with a pressurereducing device 89 adjustable by the screw 90. A conduit 9! from the fitting 88 is connected to aT-fitting 92 and respectively to the pressure gauge 82 and the tubular screw 59. As shown in Figs. 1, 8, 13 and 15, the valve 84 includesa rotatable valve stem 85a operated by the rod 85, angle ports 85b and 850 in the valve stem forming communication with the conduits 83 and 81 for the passage of fluid to the ports to be operated. The ports 85b The locking pin 98 is normally spaced from,

and'85c also form communication between the conduit 81 and bleed port 84a in the valve 84 for exhausting the fluid from the apparatus and shutting off the supply from conduit 83. When the treadle 86 shown in Figure 8 is depressed, fluid under pressure is delivered to the apparatus and when the treadle 8611' is depressed the supply is cut off and the fluid exhausted to atmosphere. With the treadles positioned as illustrated by full lines, both the supply and exhaust are cut off and the fluid operated ports are under pressure of the fluid.

When the supply of air to the conduits 83-is cut off by the valve 84, air in the conduits 81 and the branch conduits extending therefrom lead through the valve 84, the gauge 82 registering zero, the locking pins 98 being disengaged from the ratchet base plates 2? and 58 by means of the springs 99 while the spring '84 holds the piston 63 at the end of the cylinder '62 adjacent the upper end of the block 59. A tennis racket 54 is placed upon the blocks 53 at the upper ends of the blocks 40 and 44 and also upon the block 58 upon the inner end of the screw 5'1, the screw 5'! being adjusted to cause the pins 55a to cooperate with the pins 55 on the block 46 for engaging the tennis racket frame. Turn buckle screw 45 is then adjusted to cause the pins at the upper ends of the blocks 53 associated therewith to be moved into engagement with adjacent parts of the tennis racket to efiect a rigid support for the latter upon the upper end of the turret. The spindles 50 may be vertically adjusted and the turret 26 rotated to aline desired openings in the tennis racket 54 with the string tensioning device 5?, the latter being also rotatably adjustable to accomplish such alinement. The gripping jaws T3 are :then shifted upon their link supports E5 to the position shown in Figure 5 for the placement of a tennis racket string it! therebetween and at which time the jaws are released and permitted to return to clamping position relative to the string 8| as shown in Figure 6. The valve shaft is then operated by the treadle 8'6 for registering the an le ports 85b and 85a with the fluid inlet conduit 83 and conduit 81 and permitting the flow of air through the conduit 83, valve 84 and to the conduit 8! for delivery to the diaphragm devices under full pressure and through the pressure reducing device 89 to the gauge 82 and cylinder 62 for operation of the piston 53, movement of the piston which carries the string gripping jaws l3 placing the string 8! under tension as will be obvious from an inspection of Figure 3. When the desired tension has been placed upon the string Bl which will be indicated upon the gauge 82, the valve stem 85a is moved to the position shown in Figure 15 and a wedge key or the like is inserted in the string opening in the tennis racket 54. The pressure devices are then released by depressing the treadle 88a to register the conduit 8'5 with the bleed opening 841: and the turret 26 is adjusted to present adjacent string openings in line with the tensioning device 5?.

From the above detailed description of the invention, it is believed that the construction and operation thereof will at once be apparent and while there is herein shown and described the preferred embodiment of the invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

I claim:

1. In apparatus for stringing rackets, 'a stand, J

a racket turret support and a stringtensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, and pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer.

' 2. In apparatus for stringing rackets, a stand, a racket turret support and' a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which aracket' is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for holding theturret support and tensionizer against rotation and operating the tensionizer, the turret support including a rotatable ratchet plate, and horizontally and vertically adjustable supports above the ratchet plate for a racket.

3. In apparatus for'stringing rackets,astand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjusted, pneumatically operated means for holding the turret support and ten-v sionizer against rotation and operating the'ten sionizer, the string tensionizer including a cylin der having a slot therein, a piston reciprocating in the cylinder, a sliding block exteriorly of the cylinder and having a part extending through the cylinder slot for attachment to the piston, string gripping jaws movably carried by the block, the

working faces of the jaws having file characteristics to increase gripping engagement with a string and means for normally holdingthejaws in string gripping position. i

4. In apparatus for stringing rackets, a stand,

a racket turret support and a string tensionizer at .1

the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for izer including a cylinder having a slot therein, 'a-

piston reciprocating in the cylinder, a sliding block exteriorly of the cylinder and having a part extending through the cylinder slot for attachment to the piston, string gripping jaws movably carried by the block, the working faces of the jaws having file characteristics to increase gripping engagement with a string and means for normally holding the jaws in string gripping position.

5. In apparatus for stringing rackets, a stand,

a racket turret support and astring tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operate-d meansfor holding the turret support and-tensionizer against rotation and operatingthetensionizer;

the turret support including a rotatable ratchet V plate, horizontally and vertically adjustable sup ports above the ratchet plate for a racket, pins rising from the racket supports and rubber shields on the pins, the string tensionizer including a cylinder having a slot therein, a piston're- V ciprocating in the cylinder, asliding block exteriorly of the cylinderiand having 'a part extending through the cylinder slot for attachment to the piston, string grippingjaws movably carried by the block, the working faces of the jaws having file characteristics to increase gripping engagement with a string and means for normally holding the jaws in string gripping position.

6. In apparatus for stringing rackets, a stand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer, the pneumatically operated means including tensioned locking pins for the tensionizer and turret support, a diaphragm chamber associated with each pin, manually controlled means for feeding fluid under pressure to the diaphragm chambers and tensionizer, a gage on the stand, and a pressure reducer interposed in the fluid line between the source of supply and the gage and tension izer.

7. In apparatus for stringing rackets, a stand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer, the turret support including a rotatable ratchet plate, horizontally and vertically adjustable supports above the ratchet plate for a racket, the pneumatically operated means including tensioned locking pins for the tensionizer and turret support, a diaphragm chamber associated with each pin, manually controlled means for feeding fluid under pressure to the diaphragm chambers and tensionizer, a gage on the stand, and a pressure reducer interposed in the fluid line between the source of supply and the gage and tensionizer.

8. In apparatus for stringing rackets, a stand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer, the turret support including a rotatable ratchet plate, horizontally and vertically adjustable supports above the ratchet plate for a racket, pins rising from the racket supports and rubber shields on the pins, the pneumatically operated means including tensioned locking pins for the tensionizer and turret support, a diaphragm chamber associated with each pin, manually controlled means for feeding fluid under pressure to the diaphragm chambers and tensionizer, a gage on the stand, and a pressure reducer interposed in the fluid line between the source of supply and the gage and tensionizer.

9. In apparatus for stringing rackets, a stand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjusted, pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer, the string tensionizer including a cylinder having a slot therein, a piston reciprocating in the cylinder, a sliding block exteriorly of the cylinder and having a part extending through the cylinder slot for attachment to the piston, string gripping jaws movably carried by the block, the working faces of the jaws having file characteristics to increase gripping engagement with a string and means for normally holding the jaws in string gripping position, the pneumatically operated means including tensioned locking pins for the tensionizer and turret support, a diaphragm chamber associated with each pin, manually controlled means for feeding fluid under pressure to the diaphragm chambers and tensionizer, a gage on the stand, and a pressure reducer interposed in the fiuid line between thesource of supply and the gage and tensionizer.

10. In apparatus for stringing rackets, a stand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer, the turret support including a rotatable ratchet plate, horizontally and vertically adjustable supports above the ratchet plate for a racket, the string tensionizer including a cylinder having a slot therein, a piston reciprocating in the cylinder, a sliding block exteriorly of the cylinder and having a part extending through the cylinder slot for attachment to the piston, string gripping jaws movably carried by the block, the working faces of the jaws having file characteristics to increase gripping engagement with a string and means for normally holding thejaws in string gripping position, the pneumatically operated means including tensioned locking pins for the tensionizer and turret support, a diaphragm chamber associated with each pin, manually controlled means for feeding fluid under pressure to the diaphragm chambers and tensionizer, a gage on the stand, and a pressure reducer interposed in the fluid line between the source of supply and the gage and tensionizer.

11. In apparatus for stringing rackets, a stand, a racket turret support and a string tensionizer at the upper end of the stand, adjustable means on the turret support upon which a racket is adapted to be mounted, said tensionizer being rotatably adjustable, pneumatically operated means for holding the turret support and tensionizer against rotation and operating the tensionizer, the turret support including a rotatable ratchet plate, horizontally and vertically adjustable supports above the ratchet plate for a racket, pins rising from the racket supports and rubber shields on the pins, the string tensionizer including a cylinder having a slot therein, a piston reciproeating in the cylinder, a sliding block exteriorly of the cylinder and having a part extending through the cylinder slot for attachment to the piston, string gripping jaws movably carried by the block, the working faces of the jaws having file characteristics to increase gripping engagement with a string and means for normally holding the jaws in string gripping position, the pneumatically operated means including tensioned locking pins for the tensionizer and turret support, a diaphragm chamber associated with each pin, manually controlled means for feeding fluid under pressure to the diaphragm chambers and tensionizer, a gage on the stand, and a pressure reducer interposed in the fluid line between the source of supply and the gage and tensionizer.

12. In apparatus of the character described, a gripping member including a block, a pair of gripping jaws relatively movable on the block, the

ed from movements to positions transversely of the block and jaws when the jaws are moved to gripping positions.

13. Means for tensioning a string or the like, including a block, a pair of gripping jaws relatively movable on the block, the working faces of the jaws having file characteristics, and means for normally moving the jaws towards each other for gripping engagement with the string, anchor means for the other end of the string, and means for moving the block for tensioning the string and the mounting for the jaws including a pair of parallel links connecting each jaw to the block and projecting outwardly of the associated jaw, the links being of a length whereby they are prevented from movements to positions transversely of the block and jaws when the jaws are moved to gripping positions.

14. Means for tensioning a string or the like, including a block, a pair of gripping jaws relatively movable on the block, the working faces of the jaws having file characteristics, and means for normally moving the jaws towards each other for gripping engagement with the string, anchor means for the other end of the string, a cylinder,

a piston reciprocating therein, the block being carried by thepiston exteriorly of the cylinder and means for operating the piston and the mounting for the jaws including a pair of parallel links connecting each jaw to the block and projecting outwardly of the associated jaw, the links being of a length whereby they are prevented from movements to positions transversely of the block and jaws when the jaws are moved to gripping positions.

15. In apparatus of the character described, a gripping member including a block, a pair of gripping jaws relatively movable on the block, the

working faces of the jaws having file characteristics, means for normally moving the jaws towards each other for gripping engagement, the mounting of the gripping jaws including links connecting the jaws to the block, and themeans for moving the jaws towards each other comprising spring devices extending between the jaws and blocks.

16. Means for tensioning a string or the like, including a block, a pair of gripping jaws relatively movable on the block, the working faces of the jaws having file characteristics, means for normally moving the jaws towards each other for gripping engagement with the string, anchor means for the other end of the string, means for moving the block for tensioning the string, the mounting of the gripping jaws including links connecting the jaws to the block, and the means for moving the jaws towards each other comprising spring devices extending between the jaws and blocks.

17. Means for tensioning a string or the like, including a block, a pair of gripping jaws relatively movable on the block, the working faces of the jaws having file characteristics, means for normally moving the jaws towards each other for gripping engagement with the string, anchor means for the other end of the string, a cylinder, a piston reciprocating therein, the block being carried by thepiston exteriorly of the cylinder and means for operating the piston, the mount- 

